This proposal investigates the relation of nutritional factors to lung function and chronic obstructive pulmonary disease (COPD). The project will use three data sources to investigate the following hypotheses. First, do antioxidants protect the lung from damage caused by endogenous and exogenous oxidants? This research question will be addressed with longitudinal data from the Normative Aging Study (NAS), a prospective study of 2,280 men. Dietary intake data on vitamins C and E and betacarotene from food frequency questionnaires (first administered 1987) will be examined in relation to pulmonary outcomes over the subsequent 13-year period, including forced expiratory volume in the first second (FEV1), methacholine airways responsiveness, and incident COPD. Longitudinal evidence is needed to assess causality. Second, do lower lipid levels increase the risk of respiratory outcomes? Three data sources will be used to address this research question. Using cross-sectional data from the Third National Health and Nutrition Examination Survey, we will investigate the relation of lipid profile (total, LDL and HDL cholesterol; apolipoproteins AI and B) to lung function and to prevalent COPD risk. The relation of lipids to lung function also will be investigated in the NAS cohort. The prospective data allow consideration of questions with a time dimension, for example whether changes in lipid profile predict changes in pulmonary outcomes. Finally, cross-sectional data from China, a population with naturally low cholesterol, will be studied to consider the hypothesis in a population with a different range of exposure. We will also consider the possible joint effects of lipids and antioxidant exposures on lung outcomes, given that some of the candidate antioxidants, for example vitamin E and betacarotene, are lipid-soluble. The overall objectives are to understand how nutrition affects lung function, including absolute measures as well as rate of decline, and how nutrition affects the risk of lung disease. An integrated approach to the study of nutritional factors and their potential influences on lung outcomes is proposed.